// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating

// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel

// MIT license

(function() {
  var lastTime = 0;
  var vendors = ["ms", "moz", "webkit", "o"];
  for (var x = 0; x < vendors.length && !window.requestAnimationFrame; ++x) {
    window.requestAnimationFrame = window[vendors[x] + "RequestAnimationFrame"];
    window.cancelAnimationFrame =
      window[vendors[x] + "CancelAnimationFrame"] ||
      window[vendors[x] + "CancelRequestAnimationFrame"];
  }

  if (!window.requestAnimationFrame)
    window.requestAnimationFrame = function(callback, element) {
      var currTime = new Date().getTime();
      var timeToCall = Math.max(0, 16 - (currTime - lastTime));
      var id = window.setTimeout(function() {
        callback(currTime + timeToCall);
      }, 1000 / 60);
      lastTime = currTime + timeToCall;
      return id;
    };

  if (!window.cancelAnimationFrame)
    window.cancelAnimationFrame = function(id) {
      clearTimeout(id);
    };

  if (!window.performance)
    window.performance = {
      now() {
        // Using rAF polyfill's `lastTime` to ensure that timestamp passed into
        // rAF's callback and `performance.now()` are on the same timescale.
        return lastTime;
      }
    };
})();
